Wells are drilled in subsurface formations for the production of hydrocarbons (oil and gas). After drilling, the wellbore is completed typically by lining the wellbore with a casing that is perforated proximate to each oil and gas bearing formation (also referred to herein as the “production zone” or “reservoir”) to extract the fluid from such reservoirs (referred to as “formation fluid”), which typically includes water, oil and/or gas. In multiple production zone wells, sometimes the well is completed with system of packers, monitoring instrumentation, chemical injection valves, inflow control valves and surface control facilities (referred to as “intelligent well” or “intelligent completion”). Intelligent wells are especially useful for areas where intervention costs are high, since they allow operators to remotely monitor and change well conditions without the use of an intervention rig, reducing the total cost of ownership and optimizing production.
Organic scale results from changes in temperature, pressure, composition and flow velocity that occur between the reservoir and the production platform, creating deposits of asphaltenes, paraffins (waxes), gas hydrates and other organic deposits. Some hydrocarbons change phase when travelling from the reservoir to the surface, e.g., gases come out of solution (at the bubble point), asphaltene molecules precipitate, paraffins solidify and gas hydrates form solid deposits. Temperature changes are particularly pronounced in deepwater environments where sea floor temperatures approach 32° F. Pressure can also change dramatically from greater than 25,000 psi in the reservoir to less than 1,000 psi in surface equipment. Organic scale deposits can occur in the reservoir, in the completion, in production lines, and in surface equipment. Common types of organic scale include paraffins and asphaltenes.
Hydrocarbons can become insoluble soon after leaving the formation leading to deposits within production equipment. Driven by changes in temperature pressure, and composition equilibrium conditions will shift to favor solid-phase formation or precipitation of organic scale. Unfortunately, the formation or precipitation of organic scale can be detrimental to production equipment either downhole or at the surface due to the organic scale plugging pipes or tubing carrying produced formation fluid. Hence, apparatus and method that can anticipate and diagnose production problems caused by organic scales, can predict where organic scale may be formed or precipitated in production equipment, can assess the relative effectiveness of various preventative methods (e.g., the efficacy of different organic scale inhibitors) under downhole conditions, can provide sufficient warning to develop contingency plans and stage remediation programs, and can validate Equation of State models for produced fluids would be well received in the oil industry.